1. Field of the Invention
This invention relates generally to automotive or vehicle lifting devices, and more particularly concerns, a lifting device for a trailer which lifts the trailer such that the tires clear the ground, allowing the user to fix flat tires or other malfunctions on a site, safely, easily and quickly.
2. Description of Prior Art
Flat tires and other related malfunctions have been hazards of ground transportation since inflatable tires were first introduced. As with automobiles, trailers also employ inflatable tires which on occasion become flat or suffer other malfunctions, temporarily disabling the trailer. Once a flat tire or other malfunction occurs, the trailer has to be lifted off the ground such that its tires clear the ground, permitting the repair person to unbolt and remove the disabled wheel and replace it with a spare tire or other suitable functional wheel without jeopardizing personal safety.
Typically, hydraulic jacks are brought by repair vehicles to the site of the flat tire or other malfunction. There jacks, lift the trailer off the ground, permitting the flat tire to be repaired properly and safely.
There are several drawbacks in fixing a flat tire this way. Initially, not every trailer is equipped with a hydraulic jack, for they occupy large amounts of space, are bulky, and are rather expensive. When a flat tire occurs at a remote location, a hydraulic jack must be brought to the site of the flat tire, and operated by skilled personnel. Accordingly, bringing a crew with a hydraulic jack to a remote location to fix a flat tire or other malfunction is quite costly, involving substantial time delays and expenses.
Manually powered hand cranked jacks, usually found as standard equipment in motor vehicles, also exist to assist in repairing flat tires or other malfunctions. These jacks operate by lifting a vehicle at the frame. Specifically, these jacks are designed to lift vehicle frames located along the periphery of the vehicle.
In many trailers, the frame is inward from the periphery of the trailer. As a result, these manually powered jacks cannot reach the trailer frame due to their design limitations. Improperly using this manually powered jack to lift a trailer frame a substantial distance away from the periphery poses a serious safety risk to the repair person.
Lifting devices have also been mounted to vehicle axles. U.S. Pat. Nos. 1,343,845, 1,682,856, 1,955,649, 2,240,430 and 2,750,149 show some of these devices. Specifically U.S. Pat. No. 1,343,845 discloses an axle mounted hydraulic jack. U.S. Pat. Nos. 1,682,856, 1,955,649 and 2,240,430 disclose axle mounted mechanical jacks, while U.S. Pat. No. 2,750,149 discloses a mechanical jack of which only a portion is permanently mounted to the axle. The additional ground contacting segment is fitted within the permanently mounted portion immediately prior to use.
However, these prior art jacks exhibit a drawback in that they are oriented perpendicular to the ground. As a result of this perpendicular orientation, they are unstable. If any substantial forces are placed on the vehicle, the jack will collapse, damaging the vehicle, and possibly injuring the repair person. Therefore, a person must repair the flat tire with extreme care. Additionally, the jacks disclosed in U.S. Pat. Nos. 1,955,649 and 2,750,149 require blocks to initially elevate the vehicle prior to its retention in the elevated position by the jack.